This reseach program is designed to further the basic understanding of eye movement initiation and integration. Intracellular electrophysiological techniques, as well as stimulation studies in chronic animals, are being used to examine aspects of the cat extraocular muscle system related to the anatomic and functional organization of the abducens nucleus and lateral rectus muscle. The experiments are set up to examine: 1. the possibility that abducens motoneurons exhibit differing functional characteristics with regard to the mechanical parameters of the muscle fibers they innervate, 2. the effect of superior colliculus stimulation on eye movements in alert cats as well as the intracellular responses of abducens motoneurons and "interneurons" in acute preparations, 3. the role of the "interneurons" known to exist in the abducens motoneurons. These studies of the functional organization abducens motoneurons, "interneurons", motor unit profiles and afferents to the abducens nucleus serve to directly examine some of the components of the normal eye movement system.